The present invention relates to immunological diagnostic assays; and more particularly it relates to immunological diagnostic tests for syphilis and related treponemal infections.
Syphilis is a unique disease associated with a complex host response which may be accompanied by intermittent periods of latency and classical stage development. Neither protective immunogens nor mechanisms of host resistance have been clearly defined. Also, little information is available concerning the biological-chemical properties of T. pallidum that relate to virulence. The limitations of the model system, including the inability to sequentially in vitro passage virulent treponemes, represent serious experimental deficiencies in developing potential diagnostic assays and vaccinogens. Currently available immunodiagnosis assays for syphilis are inadequate. Routinely, a "non-specific" screening test (VDRL, cardiolipin antigen) is used which causes many false-positive reactions. For example, numerous infections and autoimmune disorders as well as syphilis cause increases in the detected anti-cardiolipin antibodies. Also, this test fails to identify significant numbers of syphilis-positive test samples. Furthermore, the antigen-specific test for confirmation of syphilis is most often the FTA-ABS slide test which requires whole organisms, fluoresceinconjugated reagents and fluorescence microscopy, which involves a time-consuming, expensive and qualitative assay. Therefore millions of serodiagnostic tests are performed each year in the U.S. alone under clearly suboptimal assay conditions resulting in a tremendous economic and emotional burden in our population. In addition, immuno-diagnosis of pinta and yaws (other human treponemal diseases) is unsatisfactory.
The present invention should markedly assist in improved diagnosis of these treponemal infections. The Applicants have evolved a strategy that permits identification and characterization of T. pallidum virulence determinants which are believed to be present in syphilis and these other pathogenic spirochetes. As an outcome of this strategy, Applicants have devised a rational and experimentally effective method for serodiagnosis of syphilis and related treponemal infections that can be used routinely with greatly improve specificity.